linux-kernel - Re: [RFC PATCH v2 4/4] madvise: avoid trying to split large folio always in cold

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Date:   Mon, 24 Jul 2023 23:26:27 -0600
From:   Yu Zhao <yuzhao@...gle.com>
To:     Yin Fengwei <fengwei.yin@...el.com>, minchan@...nel.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, willy@...radead.org, david@...hat.com,
        ryan.roberts@....com, shy828301@...il.com
Subject: Re: [RFC PATCH v2 4/4] madvise: avoid trying to split large folio
 always in cold_pageout

On Fri, Jul 21, 2023 at 3:41 AM Yin Fengwei <fengwei.yin@...el.com> wrote:
>
> Current madvise_cold_or_pageout_pte_range() always tries to split
> large folio.
>
> Avoid trying to split large folio always by:
>   - if large folio is in the request range, don't split it. Leave
>     to page reclaim to decide whether the large folio needs be
>     split.
>   - if large folio crosses boundaries of request range, skip it if
>     it's page cache. Try to split it if it's anonymous large folio.
>     If failed to split it, just skip it.
>
> Invoke folio_referenced() to clear the A bit for large folio. As it
> will acquire pte lock, just do it after release pte lock.
>
> Signed-off-by: Yin Fengwei <fengwei.yin@...el.com>

I currently don't have the bandwidth to look at this one. Minchan, can
you please take a look? Thanks.